The present invention relates to a flight control indicator for an aircraft, intended to supply the engine pressure ratio of an engine of the aircraft.
Within the framework of the present invention, the expression engine pressure ratio is understood to mean the ratio between the pressures at the inlet and at the outlet of the engine, which is known in aeronautical language by the abbreviation EPR.
It is known that a flight control indicator of this type generally includes:
means for acquiring and for processing information which determine in real time the actual value of the engine pressure ratio; and
display means which present on a display screen the engine pressure ratio, the display screen being provided with a dial graduated in values of the engine pressure ratio and with a needle whose position on the dial corresponds to the actual value of the engine pressure ratio.
Moreover, the maximum value of the engine pressure ratio is generally signaled by a particular symbol envisaged on the dial.
With such a flight control indicator, pilots often have great difficulties in evaluating the actual level of the thrust delivered by the engine in intermediate regimes, in particular on the approach to a runway.
These difficulties are heightened by the fact that the EPR ratio exhibits large variations of its maximum and minimum limits, as a function of the flight conditions and in particular as a function of the Mach number, of the altitude and of the outside temperature.
To alleviate this deficit of information, pilots often resort to the information supplied by a parameter indicator N1 (speed of rotation of the low-pressure module) of the engine. Such a known indicator N1, which can easily be read and understood, gives pilots an information item (speed of rotation) enabling them to better evaluate the level of thrust delivered by the engine.
However, this standard solution is not satisfactory since it requires the monitoring of two different indicators and the simultaneous checking of two types of information.
The present invention relates to a flight control indicator intended to supply the engine pressure ratio, making it possible to remedy these drawbacks.
Accordingly, the indicator of the type comprising;
means for acquiring and for processing information which determine in real tine the actual value of the engine pressure ratio; and
display means which present on a display screen the engine pressure ratio, the display screen being provided with a dial graduated in values of the engine pressure ratio and with a needle whose position on the dial corresponds to the actual value of the engine pressure ratio, is noteworthy according to the invention in that the means for acquiring and for processing information moreover determine in real time minimum and maximum values for the engine pressure ratio, and in that the display means moreover present on the dial a circular sector, of variable amplitude and position, which is differentiated from the background of the dial and which is delimited by two radii whose positions on the graduated dial correspond respectively to the minimum and maximum values of the engine pressure ratio.
Thus, by virtue of the invention, the circular sector, that is to say the domain of possible values for the engine pressure ratio EPR between the minimum and maximum values is continuously indicated in real time, thereby rendering the variations of the domain of values clearer to the pilots and above all supplying them with a visual and intuitive readout of the actual thrust level delivered by the engine.
Moreover, by virtue of the invention, there is good differentiation between the presentations of the actual value of the EPR ratio (displayed by the needle which makes it possible to give an accurate indication of this value) and of the domain of possible values of this EPR ratio (displayed by the circular sector which gives an overall visual indication of this domain of values). Thus, the indicator can easily be read and the various information items can be properly distinguished from one another.
Within the framework of the present invention, the expression circular sector is obviously understood to mean a part of a disk which is bounded by two radii (which respectively illustrate the minimum and maximum values of the engine pressure ratio EPR).
Advantageously, the display means are formed in such a way as to present the circular sector only when the corresponding engine is operational.
Thus, the disappearance of the circular sector from the dial makes it possible to signal to the pilots, in a simple and effective manner, a fault with the engine or the switch to degraded mode (when the information making it possible to calculate the EPR ratio is not available) or the switch to xe2x80x9creversexe2x80x9d mode (thrust reversers deployed).
Furthermore, advantageously, the circular sector exhibits a color (gray for example) which in different from that of the background of the dial.
Additionally, advantageously, the means for acquiring and for processing information comprise a full authority control system for the engine of the FADEC type, which supplies the minimum and maximum values of the engine pressure ratio.
Furthermore, advantageously, the display means moreover present on the display screen a symbol, whose position on the graduated dial corresponds maximum value of the engine pressure ratio.